There is an increasing demand for air sampling systems for military, private or individual use that are capable of sorting particles of interest (e.g., aerosol particles) from an incoming air sample. Sorting of particles enables a more rapid and accurate analysis of the contents of an air sample by reducing the amount of negligible particles in the sample prior to performing analysis techniques (e.g., such as spectrographic discrimination). Particles of interest are typically separated from other particles in an air sample and then focused onto a target or particle collection surface for further analysis.
Current particle sorting systems employ aerodynamic techniques (e.g., nozzles) for manipulating and focusing particles in a sample air stream. While such sorting systems have performed reasonably well in sorting large particles (e.g., larger than approximately 50 μm), they often perform less reliably when required to manipulate smaller particles (e.g., in the range of approximately 0.5 μm to 10 μm). Moreover, such systems demonstrate less than optimal accuracy in focusing the sorted particles onto a designated target or collection surface, due to the difficulties in balancing multiple flow streams and resultant increases in particle velocity as the stream diameter is compressed.
Therefore, there is a need in the art for an improved method and apparatus for airborne particle sorting.